1. Field of the Invention
The invention relates to modified PAI-1 proteins and nucleic acids. The invention also relates to mammalian PAI-1 ligands and modulators. In particular, the invention relates to polypeptides, polypeptide compositions and polynucleotides that encode polypeptides that are ligands and/or modulators of PAI-1. The invention also relates to polyligands that are homopolyligands or heteropolyligands that modulate PAI-1 activity. The invention also relates to ligands and polyligands localized to a region of a cell. The invention also relates to localization tethers and promoter sequences that can be used to provide spatial control of the PAI-1 ligands and polyligands. The invention also relates to inducible gene switches that can be used to provide temporal control of the PAI-1 ligands and polyligands. The invention also relates to methods of treating or preventing atherosclerosis. The invention also relates to methods of treating or preventing fibrosis.
2. Background of the Invention
Plasminogen activator inhibitor-1 (PAI-1) is a serine protease inhibitor of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA), agents that convert the proenzyme plasminogen to the fibrinolytic enzyme plasmin. Regulation of fibrinolysis by PAI-1 is an important control point for normal vascular function, as the accumulation of fibrin can lead to blood clots, while an excessive decrease in fibrin can lead to hemorrhage. PAI-1 also plays an important role in tissue fibrosis by inactivating matrix metalloproteinases as well as plasmin generation (Takeshita, K, et al., American Journal of Physiology, 2004(2):449-456), and studies that modulated PAI-1 expression in animal models have implicated PAI-1 in the pathogenesis of fibrosis after chemical or immune-mediated injury (Weisberg. A D et al., Arterioscler. Thromb. Vasc. Biol., 2005, 25:365-371).
PAI-1 has also been implicated in the pathophysiology of renal, pulmonary, cardiovascular, and metabolic diseases (Cale, J M and Lawrence, D A. Curr Drug Targets, 2007, 8 (9):971-81), as well as cancer. A number of investigations have supported a role for PAI-1 in the development of heart disease. For example, pharmacologic inhibition of PAI-1 was demonstrated to protect against antiotensin-II-induced aortic remodeling (Weisberg. A D et al., Arterioscler. Thromb. Vasc. Biol., 2005, 25:365-371). Further, attenuated development of cardiac fibrosis was observed in PAI-deficient mice after myocardial infarction compared to wild-type (Takesita, K, et al., American Journal of Pathology, 2004, 164(2):449-455. Several studies (reviewed in Sobel, B E et al., Arterioscler. Thromb. Vasc. Biol., 2003, 23:1979-1989) suggest altered expression of PAI-1 in vessel walls might contribute to coronary atherogenesis.
New reagents and methods for manipulating PAI-1 expression in heart would advance research into its role in heart disease. Further, there is a need in this area for novel reagents, treatments, and methods for inhibiting PAI-1 activity.